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p0306

K

kahaikapu

NAXJA Forum User
Location
hawaii
Aloha all. i have this p0306..I was driving and noticed my oil pressure banked all the way to 90 psi. So i popped the hood inspected connector at oil pressure sensor. The next thing i know i have this miss fire. So i take a vacuum reading and i have a needle fluctuating rapidly
(still not sure why). . so i figured burnt/bad valve..WRONG.. i replaced the cylinder head and still have the dtc. OK i need to do compression test. move injector or some how test coil rail.. i noticed the sparkplug is wet..Maybe no spark or injector dumping fuel.. Just need to vent Maybe someone with a clearer head other than mind can give one suggestions.. PLease Help
 
Year?
 
2001 cherokee man this is weird. im totally trippin out ive read alot of threads and im still lost..it back to basics.. first. i did a leak down test on the first head and i had 40% verified vacuum readings with a ase tech before removing the head.... replaced head
 
Last edited:
See if the #6 injector is working.

With the engine running, touch the injector and see if you can feel it operating or use a stehoscope, or long screwdriver held to your ear, and see if you can hear the injector working (clicking). Pull the injector connector off and see if it causes any change in engine operation.
 
ok i got 90 80 85 95 85 90 psi on each cylinder.. might be slow cranking voltage.. replaced head and gasket, lifters.. does it look off . i know the comp i low.. i also hear and see the valve while being compressed by the push rod clicks as if it is loosing pressure,, the valve slowly releases abit..weird shit going on.. please help fellow xjers..im at the end
 
vacuum gauge fluctuating rapidy 13 to 16..indicates a bad valve. but on two different head..i think maybe the lifter or cam lobe is the culprit..i can hear that vavle clicking and releasing tension..thats all i can think of faulty napa lifters.. no noise when running just when turn off..not a normal thing i think anyone?
 
well just for kicks i installed my vacuum gauge on my 89 renix..guess what the gauge fluctuates even more and i have no misses dtc or nothing lol wtf
 
If you replaced the lifters and not the cam, I think that is a big NO-NO, bad idea. And if done, you need to make sure you do it a special way with break in lube and certain RPM in the early minutes. But I am not the expert.

IIRC about 120 psi is the minimum needed!
 
ok removed coil rail.. put on spark tester.. using a drb 2. i accuated coil 1 & 3.. 1 fires 6 doesnt..hmmmm got 2 to fires. getting a coil pack late this evening.. also wet plug..
 
Ecomike said:
If you replaced the lifters and not the cam, I think that is a big NO-NO, bad idea. And if done, you need to make sure you do it a special way with break in lube and certain RPM in the early minutes. But I am not the expert.
Click to expand...

this is correct.. the cam and lifter develop their own wear patterns that match each other as they run. if you replace only one of them, the common outcome is a worn down cam lobe that will start to rattle and break a push rod eventually.
its good to jump into trouble shooting, but it looks to me like you've gotten ahead of yourself on an ignition problem.
 
Talyn said:
That is not 100% correct. You can put new lifters on an old cam and run the break in procedure. However you never put used lifters on a new cam.
Click to expand...


Thanks!!! I think I can keep that straight now!!! Been getting that story piecemeal lately, and that was the missing piece I think. That does beg the question of how to decide if the lifters can be reused, i.e. inspection of them.
 
Aloha..first i would like to thank all who helped me focus lol..ok Lesson learned.
1.NEVER use a mighty vac gauge as a vacuum gauge to diag engine mechanical concerns.
2. Coil Rails do go out . as mine wouldnt spark on No#6.verified with DRB 2
So my valve train is quiet. Only reason I replaced lifters was because of the milage 11500 and I was replacing the cylinder head. THERE was no Major wear to oem lifters when replaced. no noise etc... hope this helps someone in the future Mahalo.. 385 in the Minigrass
 
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